Nitrogen Economy

Question 1

is an essential primary macronutrient that commonly limits plant growth

Answer 1

N

Question 2

is a component of proteins and nucleic acids. It is also an integral part of chlorophyll and a component of ADP and ATP.

Answer 2

N

Question 3

T or f

Deficiency of N causes chlorosis, stunted growth, low protein content, and the plant matures early.

Answer 3

T

Question 4

Deficiency of N leads to excessive vegetative growth, lodging, and reduced yield quality.

T or f?

Answer 4

F - OVERSUPPLY of N leads to excessive vegetative growth, lodging, and reduced yield quality

Question 5

Atmosphere contains__% N2, 21% O2, and 0.04% CO2 gas

Answer 5

78% of N2

Question 6

Healthy plants contain__-__% N

Answer 6

2.0-4.0%

Question 7

N Deficiency observed on
“older leaves” or “newer leaves”?

Answer 7

Older leaves

Question 8

“Plants are more susceptible to disease & insect pests”

N oversupply or N deficiency

Answer 8

N oversupply

Question 9

Form of nitrogen in the atmosphere, this form of nitrogen must be transformed to usable forms before it is available for plant uptake

Answer 9

Nitrogen gas (N2)

Question 10

Can escape from the surface of the soil under certain conditions and is harmful to plants in high quantities.

*Basic building block of commercial nitrogen fertilizers

Answer 10

Ammonia gas (NH3)

Question 11

Soil particles attract and retain ammonium on cation exchange complexes.

This form may be directly taken up by plants

Answer 11

Ammonium (NH4+)

Question 12

Second form of nitrogen which is available for plant uptake.

Highly mobile.

In highly weathered soil, it is stored in anion exchange capacity and become less mobile

Answer 12

Nitrate NO3+

Question 13

Intermediate product in the conversion of ammonium to nitrate (nitrification). Present in low quantities, but is toxic to plants

Answer 13

Nitrite NO2-

Question 14

Must be converted to ammonium before it is used by plants. This conversion occurs with time and is know as mineralization

Answer 14

Organic nitrogen

Question 15

N in soil may come from residues, fertilizers, manures, precipitation

T or f?

Answer 15

T

Question 16

__________can reduce efficiency of unprotected nitrogen fertilizer applications.

Answer 16

Natural loss mechanisms

Question 17

A bio geochemical process through which N is converted into many forms

Answer 17

N cycle

Question 18

__-__% of soil N exists in organic form (protein, amino acids)

Answer 18

95-99%

Question 19

95-99% of soil N exists in ___ form

Answer 19

Organic form

Question 20

Conversion of organic nitrogen to inorganic (NH4-N) by microbes

Answer 20

Mineralization

Question 21

Two step process whereby organic matter is broken down by soil microorganisms into ammonium

Answer 21

Mineralization

Question 22

is the decomposition of proteins and the release of amines or amine groups (R-NH2), urea and amino acids (lysine-CH2NH2COOH; alanine-CH3CHNH2COOH).

Answer 22

1st process: Aminization

Question 23

Aminization process is carried out by the ff. Except:

Pseudomonas
Bacilli
Clostridium
Aerobacter
Serrotia
Micrococcus

Answer 23

Aerobacter

Question 24

Amines, urea and amino acids produced during aminization of organic N are decomposed by other heterotrophs with
release of NH 4 +

Answer 24

2nd process: Ammonification-

Question 25

The ff are under ammonification. TRUE OR FALSE? Bacillus, Micrococcus, Sarcina, Aerobacter

Answer 25

True

Question 26

1+1=?

Answer 26

Magellan

Question 27

The ff. Are Fate of ammonium in soil. EXCEPT 1. Plant uptake/absorption through roots 2. Nitrification 3. Microbial immobilization 4. Ion exchange & fixation in clay lattice 5. Organic matter complexation 6. Volatilization 7.Leaching

Answer 27

7. Leaching

Question 28

Conversion of inorganic N (NO3 - & NH4 +) into organic forms • Both biological and nonbiological (abiotic)process

Answer 28

Immobilization

Question 29

____takes place when organic residues are poor in N

Answer 29

Immobilization

Question 30

T or f Mobilized nutrients are not readily lost from the soil by leaching, volatilization and denitrification

Answer 30

F - IMMOBILIZED NUTRIENT

Question 31

Diploma or diskarte

Answer 31

Matug

Question 32

Addition of organic material with high C : N ratio results in depletion of soil nitrate. The activity of the decomposers is greatly stimulated and they use whatever nitrogen is present. T or f

Answer 32

T

Question 33

• C/N ratio <20 Mineralization or immobilization?

Answer 33

Mineralization

Question 34

C/N >30 🡪 Mineralization or immobilization?

Answer 34

immobilization

Question 35

enough N to satisfy the needs of decomposers & enough N for plant use. A. C/N ratio <20 B. C/N >30 C. C/N 20-30

Answer 35

C/N 20-30

Question 36

Average C/N ratio of bacteria and fungi is?

Answer 36

8:1

Question 37

• Oxidation of ammonium to nitrate • Carried out by autotrophs

Answer 37

Nitrification

Question 38

1. Good supply of NH4 + ions 2. Carbon sources (bicarbonates & CO2) 3. Population of nitrifying organisms 4. Soil pH (8.5 optimum) 5. Aerobic condition 6. Moisture content @ field capacity (60% water-filled pores) 7. Soil temperature (20-300C ) The following are factors affecting _____?

Answer 38

Nitrification

Question 39

Biological reduction of nitrate (NO3-) and nitrite (NO2 -) to dinitrogen (N2) gas and nitrous oxide (N20).

Answer 39

Denitrification

Question 40

The process is mostly carried out by FACULTATIVE ANAEROBIC BACTERIA (heterotrophs) such as Pseudomonas, Bacillus, Thiobacillus, Alcaligenes, Micrococcus and Achromobacteria

Answer 40

Denitrification

Question 41

It is detrimental to agriculture because nitrogen is lost from soil

Answer 41

Denitrification

Question 42

Warm temperature (250 C-350C optimum temp.) can affect denitrification T or f

Answer 42

T

Question 43

N loss in rice fields through: -Volatilization:__-__% -Denitrification:__-__%

Answer 43

Volatilization: 10-60% Denitrification: 5-10%

Question 44

When urea is BROADCASTED without immediate incorporation, N losses of up to 50% and more can be expected. T or f

Answer 44

T

Question 45

a pH greater than 7.5 allows for considerable loss of NH3 due to NITRIFICATION T or f?

Answer 45

False- VOLATILIZATION

Question 46

urea have greater loss than ammonium fertilizer. T or f

Answer 46

T

Question 47

The ff are Factors affecting volatilization. EXCEPT Soil pH Type of fertilizer Method of fertilizer placement Soil temperature Soil moisture Buffering capacity None of the above

Answer 47

None of the above Sila tanan factors hihi

Question 48

____ promotes volatilization. Thus, volatilization is greatest as the soil dries after reaching field capacity

Answer 48

Evaporation

Question 49

Waiting at least __ month after lime materials had been applied.

Answer 49

1 month

Question 50

In the case of ___, irrigation immediately after application. Ammophos Urea Solophos

Answer 50

Urea

Question 51

NH4+ fixation by clay minerals is generally greater in subsoil than in topsoil T or f

Answer 51

T

Question 52

In highly weathered soils, NH 4 + fixation is major. T or f

Answer 52

F= In highly weathered soils, NH + fixation is MINOR

Question 53

Ammonium fixation by 2:1 expanding clay

Answer 53

smectite, mica and vermiculite

Question 54

the loss of nitrate N as water drains through the soil profile, moving out of the range of plant rooting systems

Answer 54

Leaching

Question 55

Common on soils with low water holding capacity ✔ Sands and loamy sandy ✔ can occur in silt loam soils

Answer 55

Leaching

Question 56

NITRITE is leachable form. T OR F

Answer 56

F- NITRATE

Question 57

These are natural fertilizers in which is bound to organic molecule such as animal manure, decaying plant residues, industrial wastes and many others.

Answer 57

Organic sources

Question 58

occurs at 400-5000C and 200-1,000 atmospheres

Answer 58

Synthetic ammonia process-

Question 59

requires about 1,1000 degree C and highly purified N gas is reacted with calcium carbide to form calcium cyanamide. CaC2 + N2--------CaCN2 + C

Answer 59

Cyanamide process

Question 60

21-0-0 What fertilizer?

Answer 60

Ammonium sulfate

Question 61

Identify Chemical reactions of ammonium sulfate whether upland or lowland (NH4 ) SO4 --------2NH4+ + SO4 2-

Answer 61

Lowland

Question 62

(CO(NH2)2 What fert

Answer 62

Urea